TR6

Ok, in my continuing quest to solve my periodic stalling issues, I'm wondering what effect a worn O2 sensor might have on it. I have a LWF and, so far, aftermarket chips and a new ISV have not helped. I'm looking for other things to try. How does one tell if their O2 sensor is worn? Visual inspection?

Symptoms: When you push the clutch in, the idle will drop to about 200 before bouncing back to 800 and sometimes it doesn't bounce back at all. It seems like it is more prone to stall when the engine is cold (first starting out from the parking garage at work, for example).

ilko

O2 sensor, DME relay, fuel pump. I'd go after those 3 in that order.

sml

TR6 .. any solution to your problem or are you still living with it?

sml

I have similar symptoms ... idle dipping of approx 100 rpm .. drops to 750, bounces to 1000, settles at 850rpm - fairly consistently but sometimes it is perfect and about once per mth it has stalled. Generally worse when cold.

Tried ...
ISV has been cleaned so that it would 'rattle' freely in my hand
New Steve Wong chip
DME solder joint repairs
O2 sensor replacement
DME reset (via battery disconnect)

Would like to try an adaptation but trying to avoid dealer.

RSGulp

Intake manifold air leak usually causes this. Easy to fix (just tighten all the jubilee clips - if you see one tighten it - and don't miss the 3 just above the heads on each side) ...and it's free.

TR6

Still living with it. Have tried 3 different Steve Wong chips. But it is manageable. You just have to "ride" the rpms down to 1000 before pushing in the clutch. Usually only an issue on warm days. I did replace the O2 sensor also.

sml

It is hard to access all those jubileee clips. I think I'll try the carb cleaner trick tonight. I assume you just leave the car idling, then spray step by step around the intake areas and check for a change in idling response.

sml

Does anyone own a 964 that does NOT have a little idle bounce? Maybe they are all like that.

Regulatori

Mine does it too. It's actually more stable when I have the AC off but the second I turn it on I get the bounce. It rarely dies though....it just bounces really low like it's about to die and then shoots up again.

Shamus964

I've got the RS LWFW setup with steve wong chip and I developed the significant rev drop and idle hunt over time - due to a very dirty ISV and intake tract.

I cleaned the entire intake from airbox to runners and found that the ISV was very dirty and I had oil pooling in my lower throttle body chambers from a oil overfill from a recent shop visit. This resolved the issues for me.

Upon reassembly I put in a new airbox/airflow sensor gasket since that's a potential leak-point, and that gasket is supposed to be changed whenever you separate the two. A side benefit to doing this is that all the rubber gaskets and hoses are good and tight when you're done.

Another possible cause of this could be a resonance flap that stuck partially open. You should be able to hear it cycle when the ignition key is turned on, prior to startup.

RSGulp

Me... RS lighweight... LWF... Idles absolutely perfectly at start-up all year round.

There's really no need for a 964 to 'hunt' for revs. I'm sure most peoples problems are intake leaks as the rubber seals get slack over time.

sml

i can hear the cycle of the resonance flap with the ignition key on/off.
how do i know if it is partially stuck open?

sml

What about after start-up? eg whilst warming up and whilst hot?

TR6

Even when it is over 100 degrees F outside, the oil cooler fan is running, the air conditioning running full tilt, and you are stuck in afternoon stop and go traffic? That is when mine stalls the worst.

RSGulp

Air-conditioning? 100degrees outside??

You're forgetting I drive an RS Lightweight in the UK...!



But seriously, it settles into a nice smooth idle about 5-10 secs after start-up and will then run smoothly all day in all conditions.